1. Field of the Invention
This invention relates to an embroidery sewing machine to which one of a plurality of embroidery frames is exchangeably attached.
2. Description of the Related Art
There have conventionally been provided sewing machines to which one of a plurality of embroidery frames is exchangeably attached according to the size of a workpiece cloth or the area of a sewing region. In the sewing machines of this type, the type of an attached embroidery frame needs to be detected in order that an origin of the sewing region may be determined or the sewing region may be detected. For example, JP-A-6-319880 discloses a sewing machine comprising a rock arm extending downward from a distal end of a sewing arm and a retractable lever mounted on a lower end of the rock arm. In the disclosed sewing machine, the embroidery frame is moved in the positive and negative directions on the X-axis while an abutting portion provided on the lower end of the retractable lever is located within the attached embroidery frame, so that the abutting portion is caused to abut both front and rear of the embroidery frame. The size of the attached embroidery frame is detected on the basis of two locations of the abutting portion.
In the foregoing sewing machine, however, the embroidery frame is attached to the sewing machine and subsequently moved in the two X directions so that the type of the embroidery frame is detected. As a result, the detection of the embroidery frame type takes much time. Further, when the operator has attached an erroneous embroidery frame or an embroidery frame with a sewing region which does not correspond to embroidery data, the operator is informed of the error by means of an error message or the like after the embroidery frame has been attached and its type has been detected. The operator needs to detach the erroneous embroidery frame, rearrange the workpiece cloth onto a correct embroidery frame, and attach the correct embroidery frame to the sewing machine. Thus, replacement of embroidery frame results in waste of time and labor.
As another example, JF-A-2002-52283 discloses an embroidery sewing machine in which one of a plurality of embroidery frames is exchangeably attached to a carriage of an embroidery frame moving mechanism provided on the sewing bed. In the disclosed construction, each embroidery frame includes a connecting portion having concavo-convex patterns (presence or absence of projection) formed at three juxtaposed detecting positions respectively and peculiar to every type of embroidery frame, whereby a detected portion indicative of a type of the embroidery frame. On the other hand, three detecting switches (microswitches) are provided at the carriage side so as to correspond to the detecting positions respectively. The detecting switches detect the respective concavo-convex patterns (presence or absence of projections at respective detecting positions), whereby the type of the attached embroidery frame is determined. This construction, however, requires three detecting switches, thereby complicating the structure for detecting the type of the embroidery frame. Additionally, since the type of the embroidery frame is detected after the embroidery frame has been attached, loss of time also occurs when a wrong embroidery pattern has been attached.
Therefore, an object of the present invention is to provide an embroidery sewing machine which has a function of detecting the type of a n embroidery frame and which can detect the type of the embroidery frame in a shorter period of time and can reduce the lost time in attachment of a wrong embroidery frame.
The present invention provides an embroidery sewing machine in which a workpiece cloth is moved so that an embroidery pattern is formed thereon, the embroidery sewing machine comprising a plurality of types of embroidery frames differing in a size and/or a shape from each other and holding the workpiece cloth, the embroidery frames being selectively used, a carriage, a moving mechanism moving the carriage independently in two directions perpendicular to each other, a frame holder to which the embroidery frames are selectively attached, the frame holder including a holder body fixed to the carriage and a movable holder mounted to one of a plurality of positions corresponding to the respective types of the embroidery frames relative to the holder body so that the position of the movable holder is exchangeable, a detector detecting a position of the movable holder relative to the holder body, and a determining unit determining the type of the embroidery frame based on a result of detection by the detector.
Before attaching a desired embroidery frame to the frame holder, the operator changes the position of the movable holder relative to the holder body of the frame holder corresponding to the type of the embroidery frame. The position of the movable holder is then detected by the detector, and the type of the embroidery frame is determined by the determining unit. In this case, since the type of the embroidery frame is detected before the embroidery frame is attached to the frame holder, the detection of the type of the embroidery frame can be carried out in a shorter period of time. Further, when a wrong embroidery frame is to be attached to the frame holder, an alarm can be given before attachment. This can save a time required to replace the attached embroidery frame by a correct one and a time required to change workpiece cloths.
In a preferred form, the detector includes a detected body provided with a plurality of detected portions corresponding to the embroidery frames respectively and a detecting element detecting the detected portion of the detected body. As a result, the arrangement of the detector can be simplified. In this case, the detected body is mounted on the movable holder and the detecting element is mounted on either the holder body or the carriage. Alternatively, the detected body is mounted on either the holder body or the carriage and the detecting element is mounted on the movable holder. In each case, the detector detects the detected portion of the detected body, so that the position of the movable holder relative to the holder body can reliably be detected. Further, when the detecting element is fixed to the carriage, the wiring arrangement from the detector can be simplified as compared with the case where the detector is provided at the movable holder side. Consequently, the wiring structure can be simplified.
In another preferred form, the detecting element includes a rotary potentiometer having a detecting member brought into contact with one of the detected portions of the detected body. The rotary potentiometer itself is relatively inexpensive and a single detector can detect a plurality of detected portions. Consequently, the detector can be simplified in the arrangement and rendered inexpensive.
In further another preferred form, the detected portions of the detected body have heights or widths differing from each other along a direction in which the movable holder is moved respectively. Alternatively, each detected portion of the detected body includes a tapered face having a height or a width changing therealong. In each case, the arrangement of the detected body can be simplified.
In further another preferred form, the holder body includes a guide mechanism guiding the movable holder to one of the positions by sliding movement and a positioning mechanism positioning the movable holder at the one of the positions. Consequently, the operator can easily displace the movable holder. Further, the movable holder can reliably be fixed to each position when the holder body includes a fixing mechanism fixing the movable holder positioned by the positioning mechanism to the holder body. In this case, the positions at which the movable holder is positioned by the positioning mechanism correspond to the detected portions of the detected body respectively.
As more concrete construction of the frame holder, each embroidery frame has both sides opposite to each other, and the frame holder is formed generally into a C-shape and includes a body fixed to the carriage and extending in one direction, the body of the frame holder having both ends, and two arms extending substantially perpendicularly from the ends of the body to support both sides of the embroidery frame respectively. In this case, the holder body of the frame holder includes the body and either one of the arms, and the movable holder includes the other arm mounted thereon so as to be displaceable relative to the body of the frame holder. Alternatively, each embroidery frame has both sides opposite to each other, and the frame holder is formed generally into a C-shape and includes a body fixed to the carriage and extending in one direction, the body of the frame holder having both ends, and two arms extending substantially perpendicularly from the ends of the body to support both sides of the embroidery frame respectively. In each case, the embroidery frame can be supported at two portions thereof, whereupon the embroidery frame can be moved with high rigidity.